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What fuse is this?

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I would say that a 4A 250V fuse would do the job
 
Before replacing the fuse you have to look at the glass and see if the fuse has blown very quickly or if just a small part of the fuse has "burnt through."
If it has "blown very quickly" you may have a short in one of the diodes.
Just use one strand of wire from a length of flex and solder it to the ends of the fuse. Turn on the device and see the wire droop when it is turned on.
This will let you know the suitability of the fuse.
 
Actually I don't think a 3AG of AGC type fuse will fit here. I don't remember the designation, but this looks like a mini fuse. A common 3AG or AGC fuse is about 1-1/4" long and about 1/4" diameter. I think the fuse you are showing is about 13/16" long and about 3/16" diameter. This size is much less common but not rare.

I have in my fuse junk box fuses stamped "T5AL 250V", obviously 5 amp equivalents of your fuse. The end of the cap is stamped "LF" (nested letters) which I'm guessing indicates LITTLEFUSE brand.

You can probably find a replacement at Radio Shack or a local electronics supply store if you have any nearby. Alternatively, email an inquiry to Digikey, Mouser, Jameco or other mail-order house. Take your blown fuse with you or send ALL info stamped into the fuse caps with your inquiry. It is clearly a 4 amp 250 volt fuse. The other info on the caps probably give the speed of blowing relative to overload current for the fuse. Try to get the identical designation. I also have "F1AL 250V" and they are probably a different speed.

The FU901 in the photo is clearly the component designation in the specific instrument and has nothing to do with the fuse type. The "T4AL 250V" is the important identifier of the specific fuse properties.

awright
 
I wouldn't waste too much time trying to find the perfect fuse as there may be a more serious problem which caused the fuse to blow. Just find a fuse with the same current rating, 4 amp, and use jumper wires if it doesn't fit and see if it blows again. If it does then you have a much bigger problem on your hands then just finding an exact replacement fuse, don't you ;)

It's been my experience that fuses seldom just burn open on their own and while input voltage spikes can sometimes cause that most of the time there is some other more serious problem in the circuit board or it's load devices.

Lefty
 
Thanks all, appreciate the help! I believe I do know the underlying problem and am in the process of repairing that, so the next fuse I use *hopefully* shouldn't blow.

Also, I did check and the fuse is the 5mm x 20mm mini fuse size. It's stamped T4AL250V one one side and the following on the other side:

CCC (in a circle)
RU (with a backwards "R")
SA (in a circle)
S (in a circle)
VDE (in a triangle of sorts)
something like an "m" or the flux symbol (in a circle)
50T
H (in a circle)


In looking at fuses on digikey, there are different types like:

Fast Acting, Short Time Lag
Slow Blow, Long Time Lag
etc...

Does it matter which type I use?
 
"Does it matter which type I use? "

Follow my advice and you will be able to work it out yourself.
 
CCC (in a circle)
RU (with a backwards "R")
SA (in a circle)
S (in a circle)
VDE (in a triangle of sorts)
something like an "m" or the flux symbol (in a circle)
H (in a circle)

Those are all voodoo symbols, and mean absolutely nothing whatsoever.
 
Follow my advice and you will be able to work it out yourself.

I'm really not interested in buying a bunch of fuses and soldering some wire to them, turning it on, and watching what happens. I'd just like to know what type of fuse to use, if it matters at all, so I can make the replacement.
 
From the looks of it, that's the input to a switching regulator. It probably has an inrush current protector in series with the line and you probably want to use a normal-acting fuse.
 
From the looks of it, that's the input to a switching regulator. It probably has an inrush current protector in series with the line and you probably want to use a normal-acting fuse.

No. If the fuse dips when the supply is turned on, you need a delay fuse.
Some delay fuses have a bead of solder in the middle. Others have a spring at the end.
A delay 4 amp fuse is really a 6 amp fuse with a bead of low-temperature solder in the middle that melts when the fuse wire gets hot.
 
Where did OP say the fuse dips?

Yes, I know about slow-blow fuses. Avoid them.
 
The fuse is part of a power supply for a LCD TV, if that makes a difference.

So supposing I need a delay fuse, that means I want a "long time lag"?

Forgive my in-expertise here, just trying to make sense of something I haven't worked with before.

Edit: So avoid slow-blow...normal-blow or fast acting then?
 
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As I said before. Turn on the power supply and if you see the wire in the fuse dip when the inrush of current is present, you know the fuse will eventually get over-stress and "burn out" (just fracture in the middle).
The answer is to fit a delay fuse.
I have serviced 35,000 TV sets and replaced hundreds of fuses. I have absolutley no idea what fault applies to your power supply but a delay fuse is the answer to something that takes a heavy inrush of current.
 
A "slow blow" delay fuse is the answer if you need to throw protection out the window and wait for everything to blow before the fuse does. I might use one on a motor, that's about it.

and solder it to the ends of the fuse.

I've tried soldering wires to fuses before, you wreck them half the time.
 
Ok, so get a fast acting low time lag fuse and watch the wire inside it when I power it up. If it deforms, the fuse will probably go out in the future. If this sounds right, then I'm good to go. Your suggestions make sense. Thanks all!
 
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